U.S. Department of Transportation
Federal Highway Administration
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The Swiss Council for Accident Prevention is a private, politically independent foundation, which has been legally entrusted with the task of preventing accidents in the areas of road traffic, sports, home, and leisure. Tables 4 and 5 include comparative information given to the team members by Mr. Paul Reichardt of the Swiss Council. Table 4 gives the impression that the United States has a very serious problem. However, when the raw data are normalized with millions of km driven (table 5), the United States is comparable with the best of the countries cited. The United States and the countries that the team visited are highlighted in the tables. The data are from the International Road Traffic and Accident Database (IRTAD).
At night, a human's visual capabilities are impaired, and visibility is reduced. Road crashes at night are disproportionately high in numbers and severity when compared with the daytime. In the United States, while only 25 percent of the travel occurs during nighttime, about 55 percent of the fatal crashes occur after sunset. Weighted for km traveled, the nighttime fatality rate is three times the daytime figure. 5 The major factor contributing to this problem is darkness, because of its influence on a driver's behavior and ability. Thus, logically, road lighting is a potential countermeasure.
Most of the countries reported significant safety benefits in term of crashes, injuries, and fatalities when road lighting was installed. Some sample statistics follow
In Finland, traffic fatalities were lowered from 1,000 in 1971 to 410 in 1998. Because there are long periods of darkness during the year, it is likely that roadway lighting can be credited for some portion of the decrease in fatalities.
Swiss representatives reported that crash rates are lower in appropriately lighted tunnels than on other roadways.
Arguably the best data on this subject are available in the technical report, Road Lighting as an Accident Countermeasure, CIE 93,1992. The report includes rigorous analysis of 62 lighting and crash studies from 15 countries. Eighty-five percent of the results show that lighting was beneficial, with about one-third of these studies having statistical significance.
These data lead to the general conclusion that road lighting on traffic routes will reduce the incidence of nighttime accidents. Depending on the class of road and the accident classification involved, the statistically significant results show reductions of between 13 and 75 percent. Some of the specifics are:
|Motorways and semi-motorways||20|
|Other roads for motorized traffic||25|
The Swiss have launched an ambitious program known as "Vision Zero" (figure 51). Its purpose is to improve roadways Figure 51. The Swiss "Vision Zero" program. such that there are "no fatalities in traffic accidents." The graphs in figure 52 show the number of road accidents from 1945 to 1995 as compared with the number of vehicles on the road during the same period.
Figure 51. The Swiss "Vision Zero" program.
Figure 52. Road accidents compared with numbers of vehicles.
Finnish representatives referred to an interesting experiment that was conducted in southern Finland. The road lighting was reduced from 1.5 cd/m2 to no lighting at all. The result was a 25 percent increase in the accident rate. When the lighting was reduced from 1.5 cd/m2 to 0.75 cd/m2, the accident rate increased 13 percent.
The Finnish Road Administration offers incentives to road district personnel who implement creative safety improvements. A monetary reward is provided if accident rates are reduced.
Based on the Dutch experience with reduced lighting levels during the energy crisis, light levels on motorways have been reduced to the range used in the United States, apparently without a noticeable increase in accident rates.
Dutch designers installed an experimental, dynamically lit roadway that can be operated at three lighting levels, depending on the amount of traffic and weather conditions. The normal level is 1 cd/m2, the high level is 2 cd/m2, and the low level is 0.2 cd/m2. Experts were unable to detect statistical differences in accidents between 1 cd/m2 and 2 cd/m2; however, the sample size was very small. Accident rates for the 0.2-cd/m2 system, when it is operated at low traffic volumes, have been acceptable, and a second system that only operates at 1 cd/m2 and 0.2 cd/m2 has been installed.
In Switzerland, the Zurich police provided the panel with an extensive investigative report on accidents in the Gubrist Tunnel, where there have been 75 accidents over a 30-month period. The investigation included an analysis of the lighting in the tunnel and videotape of a number of accidents. The panel found it highly interesting that the police were analyzing the causes of crashes.
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